Insulator compartment and control therefor



June 4, 1957 R. G. STREUBER ET AL 2,794,847

INSULATOR COMPARTMENT AND CONTROL THEREFOR Original Filed April 22, 1952 2 S hee ts-Sheet .IIIIIIIIII'III'I ATTORNEY June 1957 R. G. STREUBER ETAL 2,794,847

INSULATOR COHPARTHENT AND CONTROL THEREFOR Original Filed April 22, 1952 2 Sheets-Sheet 2 INVENTOR HARRY L.RICHARDSON a RUDOLF 6.5TREUBER BY {MM 2144;

ATTORNEY United States Patent INSULATOR COMPARTMENT AND CONTROL THEREFOR Rudolf G. Streuber, Bridgewater Township, Somerville,

N. J., and Harry L. Richardson, Pittsburgh, Pa., assignors to Research Corporation, New York, N. Y.', a corporation of New York Original application April 22, 1952, Serial No. 283,634. Divitslgg and this application May 21, 1953, Serial No. 356,

4 Claims. (Cl. 17418) This invention relates to improvements in insulator compartments and controls therefor, associated with electrical precipitation apparatus, and is particularly directed to an improved insulator compartment that will remain operable under wide fluctuations in the precipitator gas pressure, and to means for removing foreign liquids and gases which accumulate in the compartment.

This invention is a division of application Serial No. 283,634, filed April 22, 1952.

In electrical precipitators the discharge electrode system is generally at high electrical tension while the collecting electrodes and precipitator shell are generally grounded. High tension insulators are required for bringing the high tension conductors into the precipitator chamber. To prevent deposition on the insulator of a coating of conducting materials, it has been the general practice to provide a gas tight seal between the main chamber of the precipitator and the insulator chamber.

One form of gas tight seal comprises an annular trough filled with insulating oil or other suitable insulating fluid, and an inverted cup-shaped hood, the lower edges of which extend below the surface of the oil; the conductor extends through an opening in the top of the hood. This type of gas tight seal has not proven entirely satisfactory, as such oil seals can only be set for a limited range of pressure difi'erences between the internal precipitator pressure and the external atmospheric pressure.

When the internal pressure changes suddenly, for example, when a damper in the precipitator flue is closed, the levels of the oil at the two sides of the hood change rapidly and the oil is often ejected from the insulator compartment. Contamination of the oil seal also affects its efficient operation. Industrial gases treated by electrical precipitation are dirty and frequently saturated with water, acids or other liquids which change the specific gravity and the volume of the insulating oil. These changes in turn affect the pressure balance in the insulator compartment and prevent its proper operation.

It is therefore an object of the invention to provide an improved form of seal for closing the opening in the wall of the gas chamber while obtaining suitable electrical insulation between the chamber and the high tension electrical conductor. A further object is to provide a liquid seal which is so shaped that the liquid can assume different levels in the seal with changes in gas pressure without loss of the sealing liquid. A further object is to provide control means for an oil seal to maintain substantially constant the specific gravity of the insulating oil. A further object is to provide means for removal of contaminating liquids and gases to maintain the oil volume substantially constant and to prevent short circuits and explosions in the insulator compartment.

These and other objects and advantages of the invention are provided by the novel insulator compartment comprising an insulator chamber, conduit means connecting the upper end of the insulating chamber and the precipitation chamber, a support including an insulator Patented June 4, 1957 axially disposed in the insulator chamber, means for shutting off gaseous communication between the insulator chamber and the precipitation chamber comprising a ring through which the support passes, the walls of the insulat ing chamber and the ring defining an annular trough for the reception of an insulating liquid, a hood carried by the support concentric with the ring, the lower edge of the hood extending into the annular trough and the upper end of the hood being positioned substantially below the conduit means connecting the insulator and precipitation chambers and means for removing foreign matter from the insulating liquid whereby the volume and specific gravity of the liquid is maintained substantially constant.

The invention will be more fully described with reference to the illustrative embodiments of the invention shown in the accompanying drawings, in which:

Fig. l is a diagrammatic view in partial section of an electrical precipitator with insulator compartments constructed in accordance with the principles of the invention;

Fig. 2 is an enlarged sectional view of one form of the insulator compartment of the invention with control means for the insulating oil; and

Fig. 3 is an enlarged sectional view of the insulator compartment shown in Fig. 2 with a modified form of control means for the insulating oi].

With reference to the drawings and in particular to Figs. 1 and 2, 10 is the shell of an electrical precipitator and 12 and 12' are the shells of the insulator compartments. The insulator compartments 12 and 12' are identical except that insulator compartment 12 does not have a conductive member extending therethrough.

A high tension conductor 14 is brought into the bot tom of the compartment 12, through insulating bushing 16 which projects within the supporting insulator 18 and connects with bus bar 20.

The individual discharge electrodes 22 are suspended from the bus bar 20, which passes through the precipitator compartment into the insulator compartment 12' and is supported by insulator 24.

Within each insulator compartment a ring 26 is supported by a horizontal partition 28 to form an annular trough 30. The partition 28 is provided with a central opening equal in size to the internal diameter of the ring 26 through which the insulators 18 and 24 pass. The upper portions of the ring 26 is of less diameter than the lower portion whereby the effective volume of the upper portion of annular trough 30 is greater than its lower portion.

Secured to the high tension conductor is a hood 32 in the form of an inverted cup, which is disposed concentrically with the ring 26 with the lower edge of the cup extending below the upper edge of the ring so that the lower edge of the hood is completely immersed in the insulating oil during the normal operating range of the particular precipitator installation.

The upper end 33 of the hood 32 is positioned a substantial distance below the lower edge of the annular conduit 34 which connects the upper end of the insulator compartments with the precipitation chamber.

Under normal operating conditions the insulating oil level will be above the lower edge of hood 32 substantially as shown in Fig. 2 of the drawings. Upon a sudden rise of the pressure within the precipitator, the oil level in the outer section of the seal falls and that in the inner section rises. Since the upper end of ring 26 is reduced in diameter the change in level between ring 26 and hood 32 takes place at a substantially low rate greatly reducing the tendency for the insulating oil to surge over the top of ring 26 and out of the insulator compartment.

When the pressure in the precipitator is reduced below the normal range the oil level between the ring 26 and the hood 32 is lowered. To prevent the sealing oil from being sucked through the annular conduit 34, through which bus bar 20 extends, when the pressure in the precipitator is thus reduced the space provided between the top 33 of the hood and the lower edge of the conduit 34 is great enough to accommodate all of the sealing oil between the hood 32 and the lower edge of the conduit 34. This form of construction substantially eliminates loss of oil during abnormal low pressure surges within the precipitator.

To remove sludge, water and acid which collect in the sealing oil, and to maintain the volume of oil in the system substantially constant, an automatic control system 84 is provided.

A settling tank 86, into which sludge, water and acid having a higher specific gravity than the insulating oil collect, is secured adjacent the lower section of the insulator compartment. The foreign matter enters tank 86 by conduit 88 which joins the tank to the bottom of trough 30.

A second conduit 90 provides sludge-free oil to the upper portion of tank 86. The settling tank has two out let conduits designated 92 and 94. Conduit 92 is connected at one end into the top of the tank and the other end of the conduit discharges into the upper section of the insulator compartment, or, as shown in the drawings, into conduit 34. Conduit 92 is adapted to remove gas and air bubbles from the separating tank. Outlet conduit 94 is connected into the lowermost portion of the settling tank and is provided with an automatic outlet valve 96. This valve may be normally held in the closed position by springs and have an electrically actuated solenoid 98 adapted to open the valve when the solenoid is energized. The electric current for the solenoid is derived from the transformer 100. One of the leads 102 from the transformer is connected to one terminal of the solenoid and the other lead 104 is connected to an electrode 106 supported within the tank 86. The circuit is completed by an electrical conductor 108 which connects the conductive wall of tank 86 to the other terminal of solenoid 98.

Since oil is substantially a non-conductor of electricity, no current will fiow to the valve actuating solenoid until the oil in the tank is replaced by conductive sludge, water or acid up to the lower end of electrode 106, at which time the electrical circuit is closed and the valve will be opened. The valve remains open until the conductive material within the tank falls to a level sufficient to break contact with electrode 106. The above cycle will operate as often as required to keep the accumulated conductive material at a predetermined level within the tank 86.

A liquid level sight tube 36 may be provided on the insulator compartment.

A modified form of the invention is shown in Fig. 3 and corresponding parts are provided with the same numerals as used in reference to Figs. 1 and 2.

With reference to Fig. 3, 12 is the shell of the insulator compartment which is divided into two sections by a horizontal partition 28. The partition has a central opening, about which ring 26 is fitted, whereby the partition, ring and the sides of chamber 12 form an annular trough 30 which is filled to a predetermined level with insulating oil. As hereinbefore described with reference to Figs. 1 and 2, the upper portion of ring 26 is of less diameter than the base portion whereby the volume of the upper and lower portions of trough 30 are different.

Secured to the high tension conductor 14 is a hood 32 in the form of an inverted cup, which is disposed concentrically with the ring 26 with the lower edge of the cup extending below the upper edge of the ring so that the lower edge of the cup is completely immersed in the insulating oil during the normal operating range of the prccipitator.

The top 33 of the hood is positioned a sufficient distance below the lower edge of the conduit 34 to provide a space between the top of the hood and the lower edge of conduit 34 to accommodate the sealing oil during abnormal low pressure surges within the precipitator.

To remove sludge, water and acid from the sealing 011 in order to maintain a substantially constant volume of oil in the system and to prevent arc-overs and possible explosions in the insulator compartment, a settling tank 38 is provided in the lower section of the insulator compartment.

A conduit 40 connects the lower portion of trough 30 with the top of the tank 38 and sludge, water and acid having a higher specific gravity than the insulating oil collect in the bottom of the tank. An outlet conduit 42 is connected at one end into the lower portion of the settling tank and connects into a sight tube 44 at the other end.

An automatic outlet valve 46 is provided on the sight tube below the union of the sight tube with conduit 42. The outlet valve 46 may be of any well-known electrically actuated type. For example, the valve may be spring urged in the closed position with a solenoid 47 for opening the valve, as to be more fully described hereinafter. The solenoid of the valve is energized when the foreign matter in the glass portion of the sight tube reaches a predetermined level. It functions by the difierenee in capacitance of the sealing oil and the foreign matter between two curved plates 48 and 50 on opposite sides of the glass tube.

The plates 48 and 50 are connected across the grid bias resistance of a triode 52. When the space between the plates is filled with oil, an extremely low electrical capacity exists and no current flows in the switch actuating coil 54. However, when acid, for example, rises in the space between plates 48 and 50 the capacity between the plates increases permitting a flow of current through coil 54 which closes switch 56 and sends an electrical signal to the electrical actuator of valve 46. The electrical signal continues to flow to the electrical actuator until oil replaces the acid between plates 48 and 50.

From the foregoing description it will be seen that the present invention provides an improved insulating compartment, and controls therefor, whereby the aims, objects and advantages of the invention are fully accomplished.

We claim:

1. An insulator compartment for an electrical precipitator having a precipitation chamber comprising an insulator chamber, conduit means connecting the upper end of the insulating chamber and the precipitation chamber, a support including an insulator axially disposed in the insulator chamber, means for shutting off gaseous communication between the insulator chamber and the precipitation chamber comprising a ring through which the suppose passes, the walls of the insulating chamber and the ring defining an annular trough for the reception of an insulating liquid, a hood carried by the support concentric with the ring, the lower edge of the hood extending into the annular trough and the upper end of the hood being positioned below the conduit means connecting the insulator and precipitation chambers, the distance between the upper end of the hood and the lower edge of the conduit means being so selected that all of the sealing oil may be accommodated between said hood and the lower edge of the conduit means during reduced pressure operation of the precipitator, and means for removing foreign matter from the insulating liquid whereby the volume and specific gravity of the liquid is maintained substantially constant.

2. An insulator compartment for an electrical precipitator having a precipitation chamber comprising an insulator chamber, conduit means connecting the upper end of the insulating chamber and the precipitation chamber, a conductor mounted in an insulating bushing axially disposed in the insulator chamber, means for shutting off gaseous communication between the insulator chamber and the precipitation chamber comprising a ring through which the conductor passes, the walls of the insulator chamber and the ring defining an annular trough for the reception of an insulating liquid, a hood carried by the conductor concentric with the ring, the lower edge of the hood extending into the annular trough and the upper end of the hood being positioned below the conduit means connecting the insulator and precipitation chambers, the distance between the upper end of the hood and the lower edge of the conduit means being so selected that all of the sealing oil may be accommodated between said hood and the lower edge of the conduit means during reduced pressure operation of the precipitator, and means for removing foreign matter from the insulating liquid whereby the volume and specific gravity of the liquid is maintained substantially constant.

3. An insulator compartment for an electrical precipitator as defined in claim 2 wherein the means for removing foreign matter from the insulating liquid comprises a tank positioned below the lowest extremity of the trough, conduit means connecting the bottom of the trough with the upper portion of the tank, valve means adjacent the lower portion of the tank and an actuator for said valve responsive to the volume of foreign matter in the tank.

4. An insulator compartment for an electrical precipitator having a precipitation chamber comprising an insulator chamber, conduit means connecting the upper end of the insulating chamber and the precipitation chamber, an insulator axially disposed in the insulator chamber, means for shutting olf gaseous communication between the insulator chamber and the precipitation chamber comprising a ring through which the insulator passes, the walls of the insulating chamber and the ring defining an annular trough for the reception of an insulating liquid, a hood carried by the insulator concentric with the ring, the lower edge of the hood extending into the annular trough and the upper end of the hood being positioned below the conduit means connecting the insulator chamber and the precipitation chamber, the distance between the upper end of the hood and the lower edge of the conduit means being so selected that all of the sealing oil may be accommodated between said hood and the lower edge of the conduit means during reduced pressure operation of the precipitator, and means for removing foreign matter from the insulating liquid whereby the volume and specific gravity of the liquid is maintained substantially constant.

References Cited in the file of this patent UNITED STATES PATENTS 913,000 Embree Feb. 23, 1909 1,889,360 Herber Nov. 29, 1932 2,099,063 Hedberg Nov 16, 1937 2,551,404 Wiggins May 1, 1951 FOREIGN PATENTS 338,827 Great Britain Nov. 27, 1930 

